{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,21]],"date-time":"2026-02-21T08:31:40Z","timestamp":1771662700024,"version":"3.50.1"},"reference-count":40,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2022,2,2]],"date-time":"2022-02-02T00:00:00Z","timestamp":1643760000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000038","name":"Natural Sciences and Engineering Research Council","doi-asserted-by":"publisher","award":["RGPIN-6907-2019"],"award-info":[{"award-number":["RGPIN-6907-2019"]}],"id":[{"id":"10.13039\/501100000038","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This work presents a rigorous and generic sensitivity analysis of silicon nitride on silicon dioxide strip waveguide for virus detection. In general, by functionalizing the waveguide surface with a specific antibodies layer, we make the optical sensor sensitive only to a particular virus. Unlike conventional virus detection methods such as polymerase chain reaction (PCR), integrated refractive index (RI) optical sensors offer cheap and mass-scale fabrication of compact devices for fast and straightforward detection with high sensitivity and selectivity. Our numerical analysis includes a wide range of wavelengths from visible to mid-infrared. We determined the strip waveguide\u2019s single-mode dimensions and the optimum dimensions that maximize the sensitivity to the virus layer attached to its surface at each wavelength using finite difference eigenmode (FDE) solver. We also compared the strip waveguide with the widely used slot waveguide. Our theoretical study shows that silicon nitride strip waveguide working at lower wavelengths is the optimum choice for virus detection as it maximizes both the waveguide sensitivity (Swg) and the figure of merit (FOM) of the sensor. The optimized waveguides are well suited for a range of viruses with different sizes and refractive indices. Balanced Mach\u2013Zehnder interferometer (MZI) sensors were designed using FDE solver and photonic circuit simulator at different wavelengths. The designed sensors show high FOM at \u03bb = 450 nm ranging from 500 RIU\u22121 up to 1231 RIU\u22121 with LMZI = 500 \u00b5m. Different MZI configurations were also studied and compared. Finally, edge coupling from the fiber to the sensor was designed, showing insertion loss (IL) at \u03bb = 450 nm of 4.1 dB for the design with FOM = 500 RIU\u22121. The obtained coupling efficiencies are higher than recently proposed fiber couplers.<\/jats:p>","DOI":"10.3390\/s22031152","type":"journal-article","created":{"date-parts":[[2022,2,6]],"date-time":"2022-02-06T20:40:18Z","timestamp":1644180018000},"page":"1152","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Optimization of Silicon Nitride Waveguide Platform for On-Chip Virus Detection"],"prefix":"10.3390","volume":"22","author":[{"given":"Raghi S.","family":"El Shamy","sequence":"first","affiliation":[{"name":"Department of Electrical and Computer Engineering, Faculty of Engineering, McMaster University, Hamilton, ON L8S 4L8, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mohamed A.","family":"Swillam","sequence":"additional","affiliation":[{"name":"Department of Physics, School of Science and Engineering, The American University in Cairo, New Cairo 11835, Egypt"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xun","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, Faculty of Engineering, McMaster University, Hamilton, ON L8S 4L8, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,2,2]]},"reference":[{"key":"ref_1","unstructured":"WHO (2021, December 30). The Top 10 Causes of Death. WHO 2017. Available online: http:\/\/www.who.int\/mediacentre\/factsheets\/fs310\/en\/."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1749","DOI":"10.1126\/science.8096089","article-title":"High levels of HIV-1 in plasma during all stages of infection determined by competitive PCR","volume":"259","author":"Piatak","year":"1993","journal-title":"Science"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Bastos, A.R., Vicente, C., Oliveira-Silva, R., Silva, N.J., Tac\u00e3o, M., Costa, J.P.d., Lima, M., Andr\u00e9, P.S., and Ferreira, R.A. (2018). Integrated optical Mach-Zehnder interferometer based on organic-inorganic hybrids for photonics-on-a-chip biosensing applications. Sensors, 18.","DOI":"10.3390\/s18030840"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"127002","DOI":"10.1117\/1.JBO.23.12.127002","article-title":"Label-free real-time optical monitoring of DNA hybridization using SiN Mach\u2013Zehnder interferometer-based integrated biosensing platform","volume":"23","author":"Murib","year":"2018","journal-title":"J. Biomed. Opt."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"681","DOI":"10.1016\/j.snb.2013.07.053","article-title":"Highly sensitive Mach\u2013Zehnder interferometer biosensor based on silicon nitride slot waveguide","volume":"188","author":"Liu","year":"2013","journal-title":"Sens. Actuators B Chem."},{"key":"ref_6","first-page":"106290Z","article-title":"Design, manufacture, and testing of a silicon nitride ring resonator-based biosensing platform","volume":"Volume 10629","author":"Bryan","year":"2018","journal-title":"Chemical 2018, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XIX"},{"key":"ref_7","first-page":"1087511","article-title":"Microring resonator biosensing platform for sensitive detection of thrombin","volume":"Volume 10875","author":"Besselink","year":"2019","journal-title":"Microfluidics 2019, BioMEMS, and Medical Microsystems XVII"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"6563","DOI":"10.1109\/JSEN.2018.2849825","article-title":"A highly sensitive metal\u2013insulator\u2013metal ring resonator-based nanophotonic structure for biosensing applications","volume":"18","author":"Hyder","year":"2018","journal-title":"IEEE Sens. J."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"821","DOI":"10.1002\/jbio.201300012","article-title":"A silicon photonic biosensor using phase-shifted Bragg gratings in slot waveguide","volume":"6","author":"Wang","year":"2013","journal-title":"J. Biophotonics"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"687","DOI":"10.1007\/s12010-015-1902-x","article-title":"A novel optical biosensing system using Mach\u2013Zehnder-type optical waveguide for influenza virus detection","volume":"178","author":"Sakamoto","year":"2016","journal-title":"Appl. Biochem. Biotechnol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"394","DOI":"10.1021\/nl062595n","article-title":"Fast, ultrasensitive virus detection using a young interferometer sensor","volume":"7","author":"Ymeti","year":"2007","journal-title":"Nano Lett."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"299","DOI":"10.1016\/j.optlastec.2018.10.059","article-title":"Silicon nitride photonic integration for visible light applications","volume":"112","author":"Porcel","year":"2019","journal-title":"Opt. Laser Technol."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Wilmart, Q., El Dirani, H., Tyler, N., Fowler, D., Malhouitre, S., Garcia, S., Casale, M., Kerdiles, S., Hassan, K., and Monat, C. (2019). A versatile silicon-silicon nitride photonics platform for enhanced functionalities and applications. Appl. Sci., 9.","DOI":"10.3390\/app9020255"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Baets, R., Subramanian, A.Z., Clemmen, S., Kuyken, B., Bienstman, P., Le Thomas, N., Roelkens, G., Van Thourhout, D., Helin, P., and Severi, S. (2016). Silicon Photonics: Silicon nitride versus silicon-on-insulator. Optical Fiber Communication Conference, Optical Society of America.","DOI":"10.1364\/OFC.2016.Th3J.1"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"195436","DOI":"10.1109\/ACCESS.2020.3032186","article-title":"Review of recent progress on silicon nitride-based photonic integrated circuits","volume":"8","author":"Sharma","year":"2020","journal-title":"IEEE Access"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1364\/OL.42.000021","article-title":"Large-scale silicon nitride nanophotonic phased arrays at infrared and visible wavelengths","volume":"42","author":"Poulton","year":"2017","journal-title":"Opt. Lett."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"26517","DOI":"10.1364\/OE.22.026517","article-title":"On-chip frequency comb generation at visible wavelengths via simultaneous second-and third-order optical nonlinearities","volume":"22","author":"Miller","year":"2014","journal-title":"Opt. Express"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2177","DOI":"10.1364\/OL.40.002177","article-title":"Visible-to-near-infrared octave spanning supercontinuum generation in a silicon nitride waveguide","volume":"40","author":"Zhao","year":"2015","journal-title":"Opt. Lett."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1171","DOI":"10.1364\/OPTICA.3.001171","article-title":"High-Q silicon nitride microresonators exhibiting low-power frequency comb initiation","volume":"3","author":"Xuan","year":"2016","journal-title":"Optica"},{"key":"ref_20","unstructured":"(2021, December 20). Optical Waveguide Design Software-Lumerical MODE Solutions Lumerical. Available online: https:\/\/www.lumerical.com\/products\/mode-solutions\/."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"911","DOI":"10.1002\/ejhf.1828","article-title":"Myocardial localization of coronavirus in COVID-19 cardiogenic shock","volume":"22","author":"Tavazzi","year":"2020","journal-title":"Eur. J. Heart Fail."},{"key":"ref_22","first-page":"1","article-title":"2019 novel coronavirus (COVID-19) outbreak: A review of the current literature","volume":"4","author":"Sahin","year":"2020","journal-title":"EJMO"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"295","DOI":"10.1149\/1.2403440","article-title":"Optical properties of silicon nitride","volume":"120","author":"Philipp","year":"1973","journal-title":"J. Electrochem. Soc."},{"key":"ref_24","unstructured":"Palik, E.D. (1998). Handbook of Optical Constants of Solids, Academic Press."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Shi, Y., Ma, K., and Dai, D. (2016). Sensitivity enhancement in Si nanophotonic waveguides used for refractive index sensing. Sensors, 16.","DOI":"10.3390\/s16030324"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"708","DOI":"10.1364\/OL.33.000708","article-title":"Label-free optical biosensing with slot-waveguides","volume":"33","author":"Barrios","year":"2008","journal-title":"Opt. Lett."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"4394","DOI":"10.1109\/JLT.2019.2924916","article-title":"Mid infrared integrated MZI gas sensor using suspended silicon waveguide","volume":"37","author":"Swillam","year":"2019","journal-title":"J. Lightwave Technol."},{"key":"ref_28","unstructured":"(2021, December 20). PIC Design and Simulation Software-Lumerical Interconnect Lumerical. Available online: https:\/\/www.lumerical.com\/products\/interconnect\/."},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Luan, E., Shoman, H., Ratner, D.M., Cheung, K.C., and Chrostowski, L. (2018). Silicon photonic biosensors using label-free detection. Sensors, 18.","DOI":"10.20944\/preprints201809.0150.v2"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"22829","DOI":"10.1364\/OE.21.022829","article-title":"Overcoming Si3N4 film stress limitations for high quality factor ring resonators","volume":"21","author":"Luke","year":"2013","journal-title":"Opt. Express"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"25827","DOI":"10.1364\/OE.23.025827","article-title":"Linear and nonlinear characterization of low-stress high-confinement silicon-rich nitride waveguides","volume":"23","author":"Klintberg","year":"2015","journal-title":"Opt. Express"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2202809","DOI":"10.1109\/JPHOT.2013.2292698","article-title":"Low-loss singlemode PECVD silicon nitride photonic wire waveguides for 532\u2013900 nm wavelength window fabricated within a CMOS pilot line","volume":"5","author":"Subramanian","year":"2013","journal-title":"IEEE Photonics J."},{"key":"ref_33","first-page":"109231M","article-title":"A compact silicon-on-insulator gas sensor","volume":"Volume 10923","author":"Swillam","year":"2019","journal-title":"Silicon Photonics XIV"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"12988","DOI":"10.1038\/s41598-019-49324-5","article-title":"A high efficiency silicon nitride waveguide grating coupler with a multilayer bottom reflector","volume":"9","author":"Hong","year":"2019","journal-title":"Sci. Rep."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"30623","DOI":"10.1364\/OE.26.030623","article-title":"Multi-layer silicon nitride-on-silicon polarization-independent grating couplers","volume":"26","author":"Mak","year":"2018","journal-title":"Opt. Express"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"5059","DOI":"10.1364\/OL.41.005059","article-title":"High-efficiency apodized-imaging chip-fiber grating coupler for silicon nitride waveguides","volume":"41","author":"Chen","year":"2016","journal-title":"Opt. Lett."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"14036","DOI":"10.1364\/OE.21.014036","article-title":"Silicon nitride CMOS-compatible platform for integrated photonics applications at visible wavelengths","volume":"21","author":"Merget","year":"2013","journal-title":"Opt. Express"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1155","DOI":"10.1364\/OSAC.2.001155","article-title":"Grating devices on a silicon nitride technology platform for visible light applications","volume":"2","author":"Song","year":"2019","journal-title":"OSA Contin."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"37400","DOI":"10.1364\/OE.27.037400","article-title":"Visible-light silicon nitride waveguide devices and implantable neurophotonic probes on thinned 200 mm silicon wafers","volume":"27","author":"Sacher","year":"2019","journal-title":"Opt. Express"},{"key":"ref_40","unstructured":"(2021, December 30). Thorlabs a Global Manufacturer of Photonic Tools\u2014THORLABS. Available online: https:\/\/www.thorlabs.com\/newgrouppage9.cfm?objectgroup_id=949."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/3\/1152\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T22:13:18Z","timestamp":1760134398000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/3\/1152"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,2,2]]},"references-count":40,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2022,2]]}},"alternative-id":["s22031152"],"URL":"https:\/\/doi.org\/10.3390\/s22031152","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,2,2]]}}}